Built and fact-checked by the DocNectar team — see our editorial standards
Key Features
Instant Calculation
Get accurate results in real time with our optimized algorithm.
Mobile Friendly
Fully responsive design. Works on all devices & screen sizes.
Privacy Focused
Your data stays on your device. We don't store any inputs.
100% Free
No hidden costs. This tool is completely free forever.
"How many months until we run out of cash" is one of the most important numbers a startup founder needs to know at all times — and one that's easy to lose track of between fundraising conversations, hiring decisions, and day-to-day operations.
This calculator takes your current cash balance, monthly revenue, and monthly expenses and works out your net burn rate and exactly how many months of runway that gives you. If you also set a target runway (say, 12 or 18 months), it tells you the maximum burn rate you can afford to hit that target.
How it works
Enter your current cash balance, monthly revenue, and monthly expenses. The tool calculates your net burn rate (expenses minus revenue) and divides your cash balance by that rate to get your runway in months. If revenue already covers expenses, it flags the business as profitable with unlimited runway. Optionally, enter a target runway in months to see the maximum burn rate that would still hit that target.
- Enter your current cash balance.
- Enter your monthly revenue and monthly expenses.
- Optionally enter a target runway in months.
- Review your net burn rate and runway.
Examples
Calculating basic runway
With $120,000 in the bank, $5,000 in monthly revenue, and $25,000 in monthly expenses, the net burn rate is $20,000/month — giving 6 months of runway.
Checking against a target runway
With the same $120,000 balance and an 18-month target runway, the maximum affordable burn rate is about $6,667/month — well below the $20,000/month actual burn, flagging the target as not currently met.
Who should use it
- Tracking how many months of cash a startup has left at its current spending rate.
- Checking whether current burn rate is sustainable against a target runway.
- Informing fundraising timing and urgency conversations with a founding team or board.
Industry applications
- Startup finance and fundraising
- Venture capital and startup advising
- Small business cash flow management
Advantages
- Calculates net burn rate and runway in one step.
- Flags profitability automatically when revenue covers expenses.
- Supports an optional target runway to check spending against a specific goal.
Limitations
- Assumes constant monthly revenue and expenses, not accounting for seasonality or one-time events.
- Doesn't factor in pending fundraising or committed but undisbursed capital.
- A single snapshot — needs to be recalculated regularly to stay accurate.
Common mistakes to avoid
- Using gross burn (total expenses) instead of net burn (expenses minus revenue) when estimating runway.
- Forgetting to update the calculation as revenue or expenses change month to month.
- Treating runway as a fixed number rather than recalculating regularly as the business evolves.
Best practices
- Recalculate runway monthly, not just once, since revenue and expenses rarely stay perfectly constant.
- Start fundraising conversations well before runway gets critically short — most raises take longer than founders expect.
- Use a target runway (12-18 months is common) to sanity-check whether current spending is sustainable.
Tips
- Recalculate immediately after any major hire, contract, or expense change — burn rate shifts faster than founders often expect.
- Share runway numbers transparently with your team when relevant — surprises about cash running low erode trust faster than the number itself.